we run Rotella 15-40 in our iron head 360. The W8 mill was dynoed with Torco TR1 10-30 and that's what I continue to use, although I do have a case of synthetic PurOL 5w-30 that I might use in the future.

http://pur-ol.com/purol-elite-series/

http://www.torcousa.com/torco_product/tr-1.html